The invitation came on a Monday, on a heavy cream card edged in green and gold, and it informed Sienna in engraved script, which must have cost somebody a week's wages, that the Governors of the Marenna General Foundation requested the pleasure of Mrs. Matteo Bellandi's company at the Winter Gala.

She read it three times at the long pine table in the kitchen, with a cup of salted coffee going cold at her elbow. Mrs. Matteo Bellandi. It looked like the name of a stranger, someone with a good coat and a calm face who had never counted the stairs in a cathedral. The date was the twenty-third of November, a Saturday. The place was the grand ballroom of the Halloran Hotel on Saint Brendan's Quay, and the dress, according to the line in smaller type at the bottom, was black tie.

"You've gone the color of a boiled egg," said Mrs. Venn from the range.

"It's the hospital's gala." Sienna turned the card over, as though the back might say something kinder. "They hold it every year. The staff are meant to attend, in rotation, to be shown to the donors like the sample cabinet. Dr. Pryce put my name on the list in August, before I was a Bellandi, and nobody has taken it off."

"Then you'll go."

"I could say I'm ill."

"You could." Mrs. Venn stirred a pot with great deliberation. "You'd be the first Bellandi wife in a hundred and forty years to send her regrets to a hospital. They'll talk about it at the christenings."

Sienna put the card down and rubbed her eyes with the heels of her hands. It was a perfectly sound argument. It was also, she thought, exactly the kind of argument Mrs. Venn had been making to the men of this house for forty-one years, in exactly that tone, over exactly that range.

Matteo found her in the library an hour later, standing at the blackboard with a piece of chalk, looking at the four rules she and he had written on it a fortnight ago. He came in quietly. His right hand was still bandaged, a lighter dressing now, a neat white wrap from the knuckles to the wrist, and he carried it a little away from his body in the way he had learned to since the fire. He saw the card on the table. He read it without picking it up.

"I'll come," he said.

"You don't have to."

"I know." He crossed to the window and stood with his good hand in his pocket, looking out at the winter garden. The cypresses were black against a flat white sky. "There will be two hundred people in that room, and some portion of them will have had a very great deal to say about us for a very great deal of time. You are going to be looked at. I would like to be standing beside you while it happens."

"You'd be standing beside me to be looked at yourself."

"I'm accustomed to it." A pause. "You are not."

She turned the chalk over in her fingers. She thought of a quay at dawn, and a man walking into a fire, and a hand held under cold water for twenty minutes without pulling away. Then she thought of a ballroom, and a crowd, and a great many people deciding what she was.

"We need rules," she said.

"I thought you might say so."

She wrote them under the other four, in her small hard capitals, with him reading each line as it appeared. One. In public, we are married. We stand close, we speak kindly, we look as though we chose each other. Two. In private, we are not performing. Not one word, not one gesture, not one look that is for an audience. She hesitated over the chalk. Then she wrote the third one more slowly. Three. He asks before he touches me, every time, even if it is only a hand at my back. I may say enough, and he stops, and no reason is needed.

He did not speak. He stood with his head bent, reading, and she saw the color come up under the line of his collar.

"Four," he said at last, quietly. "If either of us sees Dario, or Helena, or the gray car, or anything that frightens us, we say one word. And it means we leave, at once, and nobody asks why."

"Which word?"

His mouth moved, not quite a smile. "Mrs. Venn says there are eleven pears in the kitchen, and I have never once been allowed to eat one."

"Pears," said Sienna.

"Pears."

She wrote it on the board, because it was so absurd, and so exactly right, that she could not think of anything else to do. Pears. A little drawing of a fruit with a stalk. Beside it, in his slanting hand, he wrote the date.

She bought the dress on Thursday.

Nell took charge of it, because there was no way to prevent her. She arrived at the lab at five with her braids pinned up and a glint in her eye and announced that she had taken the next two hours off and would not accept a refusal. They went to a little shop on Calloway Street with a gilt sign and a bell over the door, run by a gray-haired woman with pins in her mouth who looked Sienna up and down once, said "Not blue, not black, and God help us, not beige," and disappeared into the back.

She came out with something over her arm.

It was green. It was not the plain dark green of the dress Sienna had worn to the first Bellandi dinner. It was the green of deep water under trees, a midnight green with a faint blue in it, and it was silk, heavy, liquid, cut close to the body and falling in a long clean line to the floor. It had no sleeves. It had a low square neck and a narrow waist and nothing at all that glittered. Sienna put it on in the cubicle, with Nell holding the curtain, and then stood and looked in the long glass for a very long time without saying anything.

"Well," said Nell, in a small voice. "That's the one."

"It's too much."

"It's not nearly enough." Nell's eyes were bright. "Hale. I have known you six years. I have watched you eat toast over a sink at midnight. I have never once seen you look as though you could walk into a room and not apologize for it." She sniffed. "It's the dress. Obviously it's the dress. Don't look at me like that."

Sienna put out a hand and squeezed her wrist. It was all she could manage.

On Saturday evening she came down the great curved staircase of the Bellandi villa at ten minutes past seven, with one hand on the banister and a silk shawl over her arm, and found the hall below full of lamplight and a man standing at the foot of the stairs.

He had been looking at his watch. He had been, she saw, quite deliberately looking at his watch, with the faintly bored air of a man who has been kept waiting and has decided to be gracious about it. He wore a black dinner jacket, perfectly cut, and a white shirt with a plain black tie. His hair had been brushed back. On his right hand was a thin black kid glove that hid the bandage, and on his left, beside the wedding band, sat the heavy gold signet ring, shifted over to the smaller finger. He looked severe and handsome and rather tired.

He lifted his eyes.

She was halfway down the stairs. She saw it happen. She saw the whole practiced composure of the man go out of him, as water goes out of a basin when the plug is pulled. His lips parted. The sentence he had very plainly prepared, something courteous, something light, died on them. The watch hung forgotten from his gloved fingers. He stood quite still at the foot of the stair with the lamplight on his face and looked up at her as he had looked at her on the steps of the Registry Office, as if he were trying to learn her by heart and had run out of time.

Sienna took three more steps. She stopped on the last but one, which put their eyes nearly level.

"Late?" she said.

"No." His voice was not steady. "No. I was going to say..." He stopped. He closed his mouth and opened it again. "I had a sentence."

"I can see that."

"It was a good one."

"I'm sure it was."

"I appear to have mislaid it." He drew a long breath, and she saw the flush climb out of his collar and stain the sharp line of his cheekbone. Behind him, in the arch to the kitchen passage, Mrs. Venn had appeared in her best black dress with a dish towel in her hand and an expression of such rigid innocence that Sienna very nearly laughed. "You look," Matteo said slowly, "as though somebody had gone and found the exact color of the sea at four in the afternoon, and put it on you. And I would like, if it is permitted, to say nothing further until I have had time to recover."

"It's permitted," Sienna said.

He offered her his arm. It was his left. She noticed that, and understood it, and took it, and felt through the black sleeve the quick hard pulse of a man who was trying very hard to look as if nothing had happened.

"May I?" he said, very low, as they went down the steps to the car, and his gloved hand hovered an inch from the small of her back.

"Yes."

He touched her. It was so light that she felt only the faint pressure of the silk against her skin, and then the warmth underneath. It was nothing at all, and every nerve in her body knew exactly where it lay.

The Halloran Hotel blazed like a ship.

The whole front of it was strung with white lights, and a red carpet ran down the wide steps to a line of black cars at the kerb, and photographers in dark coats stood behind a velvet rope, with their cameras raised. The quay behind it was loud and bright. A string quartet played somewhere inside. A tall doorman in a gray coat opened the door of the car with a bow, and the cold air smelled of sea and chrysanthemums and money.

Marco came round the car in his dark overcoat and handed her out. His broad face was entirely calm. He said, in a murmur that only she could hear, "Two of mine are in the lobby, miss. Two more at the service door. If you need anything, you say the word, and I'll be there before it's finished."

"Pears," said Sienna.

A flicker went across the big stoic face. It might have been a smile. "Yes, miss. That'll do."

They went up the carpet together, and the flashes went off like small lightning.

It was worse than she had imagined, and also better. The great ballroom of the Halloran rose three stories to a ceiling painted with gilded clouds, and from it hung four chandeliers like frozen fountains. There were white flowers everywhere, great banks of them. Two hundred people stood in knots across a floor of polished parquet, in black and silver and jewel colors, with glasses in their hands, and every single one of them seemed to turn at once.

She felt it travel across the room, a ripple of attention that began at the doors and ran outward like a current through water. She saw heads incline. She saw lips move behind fans and hands. She heard, quite distinctly, from somewhere on her left, a woman's low carrying whisper: "The lab girl. That's her. Can you imagine?"

Matteo's hand moved very slightly against her back.

"Enough?" he said, under his breath.

"No." She lifted her chin. "Not yet."

They began to walk. It was a long way to the middle of the room. Nell appeared out of the crowd in a column of scarlet satin with her braids piled high and her face lit with unholy delight, and kissed Sienna on both cheeks and whispered, "They're all dying. Look at them. Every one. This is the best night of my life," and was gone again into a knot of junior doctors before Sienna could answer. Dr. Pryce loomed at the edge of a pillar in a dinner jacket three sizes too large, with the expression of a man at his own court-martial. He bowed stiffly to Matteo and said "Mrs. Bellandi" to Sienna in a tone that suggested he had been rehearsing it in the mirror and had not quite forgiven her for making it necessary.

She was introduced to a great many people in the next half hour. She was introduced to the chairman of the Foundation, a pink and smiling man who pressed her hand and said she was a credit to the profession. She was introduced to three women in diamonds whose husbands owned fleets, who looked at her dress, and her hands, and her unadorned throat, and decided, in unison and without a word, that she was a person who could be spoken to slowly. She was introduced to a surgeon who wanted to talk about the cardiac wing. It was a strange experience. She was addressed. She was admired. She was assessed down to the stitches in her hem. And in the whole long glittering round, not one person asked her a single question about her work.

She understood, gradually, with a cold fine anger that began at the base of her spine, that she had been made into an ornament.

He is the dangerous thing in the room, she thought. And I am the lovely thing he has put on his arm, so that everyone may remark upon how safe he must be.

"Bellandi!"

The voice was a bellow. It belonged to a very large man with a very red face and a mane of silver hair swept back from a broad forehead, who came through the crowd like a ship through weed. He wore a white dinner jacket with a carnation in the lapel. He had a glass of champagne in one fist and an enormous gold watch chain across his waistcoat, and he clapped Matteo on the shoulder with a hand like a ham.

"Cassius Hartigan," said Matteo, evenly. "Of Hartigan Marine Assurance. He underwrites half the hulls in the harbor and a good deal of the gossip."

"Ha!" said Mr. Hartigan, delighted. "He's right. Both. And here she is. The famous bride. Let me look at you, my dear." He held Sienna at arm's length and examined her with the open, unashamed appraisal of a man pricing a horse. "Lovely. Quite lovely. I told Marguerite when I heard. I said, the boy's gone and married out of the circle. A lab girl! A girl who works for a living! I said it shows spirit, in a Bellandi, which we've not seen since the old man." He winked. "And a distinct want of dowry, ha ha. But when you've got what he's got, who needs a dowry?"

A hush had fallen around them. Sienna felt it, the way one feels a change in the weather. A dozen heads had turned. A woman with a fan had stopped fanning.

She was very aware of Matteo beside her. She felt him go still, the way he had gone still in the clinic annex, a banked cold quiet that rolled off him like frost. He had drawn breath to speak. She felt it in the sleeve against her arm.

"May I?" she said, softly, without turning her head.

A pause. It was so brief that no one else could have caught it. Then, low, with a note in it that might have been laughter, "Please."

Sienna smiled at Mr. Hartigan.

It was a very good smile. It was the one she used on Dr. Pryce when he proposed a protocol with a flaw in it, a bright, pleasant, perfectly innocent smile, and she saw something in the big red face flicker uncertainly.

"I'm told the circle is extremely exclusive, Mr. Hartigan," she said. Her voice was light, and clear, and carried very nicely. "In my line of work we call that a closed system. They have a tendency not to last. Everything inside goes on reacting with everything else, and nothing new comes in to take the heat, and sooner or later, quite quietly, it simply stops." She tilted her head. "I'd much rather be married to a man who lets in some air."

There was a silence of perhaps two seconds.

Then somebody laughed.

It was a young man by the pillar, a junior doctor in a borrowed jacket, and he clapped a hand over his mouth. The woman with the fan began to fan again, very fast. Mr. Hartigan's face went through three colors in quick succession and settled, with remarkable grace, on a roar of genuine delight.

"A closed system!" he bellowed. "Marguerite! Marguerite, come here and hear this. Bellandi, my boy, she's got you. She's got you in one!"

Matteo said nothing.

He had moved. It was a small movement, and she did not see it so much as feel it. His hand at the small of her back had shifted, no more than an inch, and she realized that he had stepped closer, so that he stood directly behind her, a long warm line of black at her shoulder. She felt his breath at her temple. She felt, through all the silk and wool between them, the slow steady beat of his heart.

He was smiling.

She did not have to turn to know it. She could hear it in his breath. It was not the thin courteous smile he wore in the long room above the quay, or the wry stiff half smile he gave her over the breakfast table. It was a smile that had got out of him without permission, wide and unguarded and perfectly happy, the sort of smile a man cannot arrange.

"Closed systems," he murmured, so low that only she could hear, "don't last."

She closed her eyes for a second. The ballroom rang around her with talk and music and the chime of glasses. A great chandelier turned slowly overhead, scattering small pieces of light across the floor. And she thought, with dizzy precision: I did not do that for the audience.

The orchestra struck up a waltz at nine.

It was Nell's fault. She had been spotted in a corner with the chairman of the Foundation, and she shoved him, bodily, and Dr. Pryce, and a surprised young surgeon into the cleared space in the middle of the floor, and the three of them stood there blinking while the music swelled. A ripple of laughter went round the ballroom. Couples began to drift out. A hundred silk skirts swirled and settled.

Matteo turned to her.

He did not say anything. He only held out his left hand, palm up, as he had held it out on the first night in the Registry Office, and waited.

"One dance," said Sienna. "It's in the rules."

"Rule one."

"I'll step on your feet."

"I have two," Matteo said gravely. "And I'm told I can spare one."

She put her hand in his.

He led her out under the chandeliers. His left hand settled at her waist, light and sure, and she lifted her right to his shoulder, and his burned hand, in its black glove, came up very carefully to meet hers. He did not close his fingers. He let them lie against her palm, barely touching, with the care of a man handling something that might break. She felt the thin stiff kid and the pad of bandage beneath it, and she felt him breathe in sharply as the contact settled.

"Does it hurt?" she said.

"Not at all."

"Matteo."

"A little." His mouth quirked. "I'd rather have this than the alternative."

They began to move.

She had expected to be clumsy. She had never learned to dance, beyond a few dreadful turns at a hospital Christmas party with an anaesthetist who smelled of cloves. But he led so quietly that she hardly knew she was being led. A slight pressure at her waist, a change in the angle of his shoulder, and her body simply went where it was asked. The music wound round them. The ballroom wheeled. They turned past the silver pillars, and the long mirrors, and the banked white flowers, and through it all he looked at her with that steady dark attention, as if there were no one else in the room.

"Don't look at me," she muttered. "You'll make me forget the count."

"I'm not."

"You are. You're doing it now."

"I'm performing," said Matteo, with infinite gravity. "Rule one. I'm looking at my wife as though I chose her."

"You are overdoing it."

"I am a man of many deficiencies, but I do not overdo." He turned her under his arm, so lightly that she felt it only as a shift of the air. "If I were overdoing it you would know. It would be much worse."

She tried not to laugh. She failed. It came out of her in a startled breath, and he looked down at her laughing, and something in his face did the thing it had done at the foot of the stairs. The practiced calm went out of it. His step faltered, by half a beat. His hand tightened at her waist, and she felt the whole warm width of it through the silk.

She knew in that moment that neither of them was performing.

She knew it as she knew the weight of a vial in her hand, with a kind of cold wonder. The rules lay behind them on a blackboard in a library, in a hand she knew as well as her own. And yet here she was, in a ballroom full of strangers, with her fingers resting on his shoulder and her pulse beating against his, doing precisely the thing she had written Rule Two to forbid. They had stopped speaking. They had stopped counting. The music had gone strange and distant, as though heard through water. She could feel the small shifting warmth of his breath against her temple and the faint scrape of his cuff against her arm and the astonishing, impossible rightness of the whole.

They turned. The chandeliers flashed past like falling stars.

Once, over his shoulder, she saw Dario Vance.

He stood beside a pillar at the far side of the floor, a slim silver figure in a gray dinner jacket, with a glass in his hand and an expression of pleasant benevolence. He was looking at them. He raised the glass a quarter of an inch, in a graceful little salute. She did not flinch. She did not say pears. She only let her gaze rest on him for a single beat, and then turned it back to the man in front of her, and tightened her fingers on his shoulder.

"He's there," she said. "By the third pillar."

"I saw." Matteo did not turn his head. "Keep dancing."

"I am."

"Good."

They went on. The waltz ran down to its last long swelling chord, and the dancers around them stopped and drew apart, and the ballroom broke into applause.

Sienna did not move.

Neither did he. They stood in the middle of the floor with his hand at her waist and hers on his shoulder, a pace apart, not touching anywhere else, and looked at each other. The applause went on. Someone whistled. She heard Nell's voice, high and delighted, crying out something that was probably not suitable for a hospital gala. And still she stood quite still, with her heart going like a bird, and looked up into a face she had once seen go gray on a Persian rug.

"Enough?" he said, almost without voice.

"No," said Sienna.

Then she stepped back, because there were two hundred people in the room, and she was a woman who knew precisely how long a silence could be held before it turned into something else.

Dario found her at the long white table where the champagne stood in rows.

She was alone for perhaps half a minute. Matteo had been called away by the chairman, with a murmured apology and a warm gloved press of her fingers, and she had gone to the table to put her hands somewhere. They were not quite steady. She stood with a glass of water, tested, and watched the dancers wheel.

"My dear girl."

He came up on her left, quite noiselessly, in the way he had. The gray jacket fitted him like a second skin. His silver hair gleamed. He took her free hand in both of his, dry and light and exquisitely gentle, and bent over it with the old courtly grace, and she felt the brush of his lips on her knuckles and managed, at the cost of her whole will, not to pull away.

"A triumph," said Dario. "The pair of you. I have been at this gala for forty years, and I never saw the room so quiet. Hartigan will dine out on it for a month." His pale blue eyes twinkled behind the thin gold rims. "Helena sends her regrets, by the way. A bad chest. She's been working too hard, as I tell her."

"I'm sorry to hear it."

"Oh, she'll mend." He let her hand go. "I have something for you. It's nothing. An old man's vanity. I could not resist."

He took from the pocket of his jacket a small flat parcel wrapped in gray paper and tied with a silver thread. She held it for a moment without opening it. It was light. It was about the size of her palm.

"Open it," said Dario. "Do. I'll be quite unbearable otherwise."

She slid the thread free. The paper fell open. Inside lay a notebook.

It was a beautiful thing. It was bound in soft dark green leather, tooled at the edges in a thin gold line, with a ribbon marker of the same green silk and a tiny brass clasp in the shape of a sprig of oak. The pages were thick and cream and faintly ruled. It smelled of fine leather and of something she could not quite place. A little brass key hung from a cord at its spine.

"For your thoughts," said Dario warmly. "Matteo tells me you keep a notebook. A scientist's habit, he says. Writing it all down at two in the morning, with the door bolted." His smile deepened. "I thought a young woman of such application ought not to be put to the indignity of a drugstore pad. And I confess I was rather struck by the idea of it. So few people write things down nowadays. They think, quite wrongly, that they'll remember."

The ballroom did not change. The music had started again, a slow dreamy melody. A woman laughed somewhere on her right. The chandeliers turned, and gold light ran along the edge of the green leather in her hand.

But the floor beneath her had gone soft as sand.

She had written in a blue notebook with a plain cloth cover. She had never carried it into a ballroom. She had never so much as shown it to a living soul, except to say that it was hers, and was not to be touched. She had written in it only in the locked library, in the lab behind a taped window, in a green room behind a bolt. She had never once named it. Not the Divergence Log. Not to Nell, or her father, or Mrs. Venn, who had put a pot of salt beside her coffee without being told.

A scientist's habit, he says. With the door bolted.

She made herself breathe. In for four. Hold for four. Out for six. She made her face do the thing she had learned at fifteen on the stairs of the house on Tern Street, on the afternoons her father came home with the look. It was a pleasant face, a grateful face, a little shy. It was the face of a woman who has been given a present.

"It's beautiful, Dario," she said. "I don't know how to thank you."

"You needn't." He patted her arm, with a dry soft pat. "Write something wonderful in it. And let an old man read it, one day."

He was gone into the crowd like a silver fish.

She stood with the green book in her hands and the whole ballroom turning slowly around her. Then Matteo was at her side, and had said something to her, and she had answered, and they were going down the long carpet through the white lights with the flashes going off in their faces and Marco's broad shoulders closing in behind them like a door.

The car was warm and dark and smelled of leather. Marco shut the door and went round to the wheel. The engine turned over softly. They slid out into the glittering traffic of the quay, with a second car falling in behind, and for several minutes neither of them spoke.

She did not open the notebook. She held it on her lap with both hands, as she would have held something that might still be hot.

"Sienna," said Matteo, gently. "What happened?"

She did not look at him. She kept her eyes on the green leather, on the little brass sprig of oak.

"Dario gave me this."

"I saw."

"He said you told him I keep a notebook." She heard her voice, flat and level, like a voice reading a test result. "He said I write in it at two in the morning with the door bolted." She lifted her head. "Did you tell him?"

There was a silence.

It was a short one. It was not the careful silence of a man deciding how much to say. She had learned its shape, by now. This one was quick and stunned and perfectly still, the silence of a man who has been handed a thing he did not expect and is looking at it from every side.

"No," Matteo said.

"Matteo."

"No. Never. Not to Dario, not to anyone." His voice had dropped. "Mrs. Venn knows you write, and she would cut out her own tongue before she mentioned it. Marco knows, and Marco would sooner swallow glass. I did not say a word. I would not. I have not so much as written the word notebook in any paper in my house." He turned fully toward her in the dark. "Sienna. Look at me. I did not tell him."

She looked.

His face, in the passing lights of the quay, was gray and quite open. There was nothing in it but dismay. He was not performing. She had spent six weeks learning to tell the difference, with a good many wrong turns, and she knew, with the certainty of long practice, that he was telling her the truth.

Which meant that Dario Vance, on a bright night in a ballroom, had smiled at her with the gentlest eyes in the city, and had lied.

Or else he had not lied. Or else he had known, all along, from some window or some wall or some pair of hands, exactly what she wrote and where.

"The door bolted," she said slowly. "He said, with the door bolted. Nobody has stood in the corridor outside my room except you. You told me so yourself."

"On a hundred nights." His voice was very low. "I have never once seen anyone else."

Outside, the lights of the harbor slid by one after another, gold and white and a deep, sullen red. The car turned onto the long hill road. The cypresses rose out of the dark, tall and straight and black, and beyond them, a long way off, a pale shape stood at the end of the garden wall that had not been there before and was not there now.

Sienna looked down at the green book, and at the little brass key on its cord.

"Pears," she said quietly. It was not a signal, and no one in the car would have taken it for one. She only said it aloud, as a woman says a small word to keep from saying a larger one.

Matteo's good hand closed over hers, over the book and the key, and held on.